Twelvers or the "Ithna Asharia" are members of the group of Shias who believe in twelve Imams. The Twelvers are the largest Shia school of thought, predominant in Iran.

Alternate names

The Twelvers are also known by other names, each connoting some aspect of the faith.

1. Shia, when this term is used it is usually in reference to the Twelvers since they are the "orthodox" variant of Shiism. Though in extended usage, it can be taken to refer to other groups as well.
2. Jafari is always taken to refer to "the Twelvers" to the exclusion of the Ismailis, and the Zaidis ("the Fivers"). The term Jafari is used as the Jafari school of thought (madhab) and deduction of jurisprudence (fiqh) was attributed to Jafar Sadiq who the Shia consider to be their 6th Imam. The founders of the Sunni Hanafi and Maliki schools of thought narrated Hadith from Imam Jafar Sadiq.
3. Imami is a reference to the Twelver belief in holy and infallible Imams after the time of the prophet Muhammad. Though the Seveners and the Ismailis also accept the concept of Imams, this term is also used exclusively for the Twelvers.

Theology

Religious law, the Sharia

The Jafari derive their Sharia, or religious law, from the Quran and the Sunnah similar to the Sunni schools of thought (madhab) Hanafi, Maliki, Shafai and Hanbali. The difference in Sunni and Shia Sharia results from;

1. Alternate interpretations of the Quran,
2. Alternate interpretation of the Hadith from which the Sunnah is derived,
   
3. Disagreement on the veracity of several Hadith,
4. The Shia non-acceptance of the "examples" and verdicts of the three first Caliphs, Abu Bakr, Omar and Uthman,
5. the concept of the Infallibility (masuum) of the Twelve Imams, or the Fourteen Infallibles (including Muhammad and his daughter Fatima Zahra), hence the Shia accept their examples and verdicts as is, if they can be proven to have been authentically related from any of them.

The concept of Imams and the Mahdi

The Shia Imams, the first of which is Ali ibn Abu Talib are viewed to be infallible. It is an important aspect of Shia/Twelver theology that they are, however, not prophets (nabi) nor messengers (rasul). The Twelvers view all religions and groups that accept prophets or messengers after Muhammad to be heathen or heretical. The last imam is believed to be hidden and will return; he is called the Mahdi.

Hussein's martyrdom

Hussein ibn Ali's martyrdom on the 10th of Muharram - known as the Aashurah - plays a significant role in Twelver theology. This day is annually commemorated with grief and sorrow; some participate in ritualised beating of their chests. This is known as Matam. In most nations with significant Shia populations one can observe large crowds in processions grieving over Hussein's martyrdom.

Some examples of Jafari jurisprudence differing from Sunni

(This list is not exhaustive nor representative of the sunni/shia dispute on religious jurisprudence)

Declaration of faith

Both shia and sunni believe that anyone who declares in public; "There is no god but God (Allah), and Muhammad is his messenger" and believes in it is to be considered a muslim. Though some Shias add: "...and Ali is the friend of God, and the heir of the messenger of God."

Accepting a scholar's verdict

The Jafari school of thought accept and encourages the concept of taqleed or "imitation" eg. that unlearned muslims choose a scholar of known virtue and knowledge and follow ("imitate") his rulings and verdicts in their daily life. Although Sunnis also have a concept of taqleed, it differs from that of the Jafaris.

Prayer

There are minor differences in how the prayer ritual is performed among sunnis and shias. During the purfication ritual in preparation of prayer (which consists of washing the face, arms, feet etc and saying of some prayers), the shia view wiping the feet with wet hands as sufficient as opposed to some of the sunnis who consider complete washing of the feet necessary. During prayer, it is Jafari view that it is preferable to prostrate on earth. Hence many Shia use a small tablet of soil (often taken from a holy site) or wood during their daily prayers upon which they prostrate. In Jafari view the hands are to be held straight down during the standing position of the prayer, while the Sunni schools of thought (except for the some of the Malikis) who hold that they should be folded. Similar to the Sunni view, the Jafari consider the five daily prayers to be compulsory, though the Jafari consider it acceptable to join the second and third prayer and the fourth and fifth during the parts of the day where they believe the timings for these prayers to overlap, most of the Jafari practice this often.

One-fifth tax

Khums is applicable on a wider range of items in Shi'a fiqh than according to Sunni interpretation.

Marriage

The concept of mut'a or "temporary marriage" is endorsed by the Jafari school of thought. The Sunni schools of thought reject it. Besides the mut'a issue, the Sunni and Jafari have similar rulings regarding the different aspects of marriage.